my last menstruation was oct 17 2017. my boyfriend and i had sex last oct 27 2017 and he cum inside. a weeks after i am expriencing nausea, abdominal pain and tenderness of breast. but earlier today nov 15 2017, i have blood in my undies. i'm not sure if this is implantation or my menstrual. can someone please help me for us to know if im already pregnant or not